1. Field of the Invention
The present invention relates to a wide range temperature control system for semiconductor manufacturing equipment using a thermoelectric element, and more particularly, to a wide range temperature control system for semiconductor manufacturing equipment using a thermoelectric element, whereby the thermoelectric element is applied to a chiller that is a temperature control device for semiconductor manufacturing equipment so as to precisely control a refrigerant in a cooled or heated state and furthermore, temperature control can be performed in a high temperature region that cannot be dealt with by an existing temperature control system using a thermoelectric element so that energy efficiency can be maximized
2. Discussion of Related Art
As semiconductor device technology is gradually enhanced, control precision of equipment applied to semiconductor manufacturing equipment also becomes important. A basic device of semiconductor manufacturing equipment is a chiller for controlling a temperature of semiconductor manufacturing equipment.
The chiller of semiconductor manufacturing equipment heats or cools a refrigerant so as to control the temperature of the refrigerant. According to the related art, various heaters and cooling units have been applied to the chiller so as to control the temperature of the refrigerant.
In a basic configuration of the chiller, the refrigerant is circulated by a circulation unit such as a pump and is provided to a working load. The refrigerant, of which a temperature is changed due to an action by the working load, is heated or cooled using a heater or a cooling device so that the temperature of the refrigerant is made uniform and the refrigerant is stored in and provided from a refrigerant tank.
The cooling device that is essentially included in the configuration of the chiller according to the related art mainly uses a mechanical method. Thus, the volume of the cooling device is large and noise and vibration thereof are severe. Thus, a method using a thermoelectric element that has less noise and a small size and that can be precisely controlled electronically is being used.
Such a thermoelectric element mainly uses a well known Peltier element and is capable of directly converting thermal energy into electric energy or converting electric energy into thermal energy. Thus, the thermoelectric element can be efficiently cooled with a relatively simple configuration and thus is mainly used for the purpose of cooling.
In general, the thermoelectric element includes a heat absorption surface and a heat dissipation surface and moves heat from the heat absorption face to the heat dissipation surface so that cooling can be performed. Since the thermoelectric element can also perform heating by reversing a thermoelectric direction, the thermoelectric element may also be used in both heating and cooling.
However, when cooling and heating are simultaneously performed by a single thermoelectric element, a situation in which the polarity of the single thermoelectric element varies so as to perform desired temperature control occurs frequently. Since there is a risk that the thermoelectric element may be destroyed and a hysteresis region may widen, it is difficult to perform precise control, and it is not easy to perform digital control using pulse. Also, when the single thermoelectric element converts heating and cooling, an appropriate heat-exchanging unit must be further configured, which causes the single thermoelectric element that can be used in both heating and cooling to be difficult to introduce.
In order to solve these problems, the present applicant has proposed a temperature control system in which a polarity of a thermoelectric module is changed into a cooling or heating mode, linear control information is obtained as an analog value through a proportional, integral and differential (PID) operation and then information corresponding to the polarity is managed in a digital manner and a control amount is managed as an absolute value of an analog output so that hysteresis can be minimized and a single thermoelectric element can be used in both cooling and heating, as disclosed in Korean Patent Registration No. 10-0817419.
For example, FIG. 1 illustrates an example of a temperature control system for semiconductor manufacturing equipment using polarity conversion of a thermoelectric element. As illustrated in FIG. 1, the temperature control system for semiconductor manufacturing equipment includes a controller 10 that applies a control signal indicating whether a voltage is supplied to a thermoelectric element 51 or a polarity of the thermoelectric element 51 is converted so as to control the temperature of the semiconductor manufacturing equipment to a setting temperature, a polarity converter 30 that converts and filters a supplied current according to the control signal of the controller 10 and converts the polarity of the thermoelectric element 51 into a positive or negative polarity so as to supply the current to a thermoelectric element (TEM) block 50, the thermoelectric element (TEM) block 50 on which a refrigerant passing through a refrigerant flow passage 52 is cooled or heated by the thermoelectric element 51 installed in the TEM block 50 using the current supplied from the polarity converter 30, and a refrigerant tank 60 that stores the cooled or heated refrigerant and supplies the cooled or heated refrigerant to a working load 4 through a circulation unit 65. When a cooling or heating operation is performed by the thermoelectric element 51, an opposite surface to a surface in which the refrigerant is cooled or heated is stabilized through a process cooling water (PCW) flow passage 31.
The controller 10 compares the temperature of the working load 4 with a predetermined setting temperature, determines whether the refrigerant is cooled or heated due to the working load 4 and applies a control signal indicating whether a voltage is supplied to the thermoelectric element 51 or the voltage is a positive or negative voltage to the polarity converter 30 based on the result of determination.
The polarity converter 30 generates and provides power to the TEM block 50 according to the control signal applied by the controller 10. The polarity converter 30 includes a DC power unit 40 that generates and provides a DC voltage required for driving, a voltage controller 20 that generates power of the DC power unit 40 as a voltage having a predetermined magnitude and a predetermined polarity according to control of the controller 10, and a voltage applying unit 31 that provides the voltage having the predetermined size and the predetermined polarity provided by the voltage controller 20 to the TEM block 50.
The controller 10 calculates the control amount using a PID operation and transfers polarity information and control amount information to the voltage applying unit 31 via the voltage controller 20. Thus, the voltage applying unit 31 controls an output to be provided to the TEM block 50.
Through this configuration, both cooling and heating can be performed on a single thermoelectric element block, durability and control precision of the thermoelectric element is improved so that the temperature control system can be manufactured to have a light weight and a small size, manufacturing costs can be reduced and maintenance can be simplified.
However, as semiconductor processes have recently diversified, the setting temperature of the refrigerant applied to the working load is out of the existing thermoelectric element response range (−10° C. to 60° C.) and is enlarged in a high temperature range (for example, 90° C. or more). However, when the thermoelectric element is used as a unit for varying the temperature of the refrigerant, a controllable temperature range is limited to about 60° C. or less due to a limitation in the thermoelectric element having a semiconductor structure. When heating and cooling are controlled using only the thermoelectric element so as to deal with a change of a setting temperature in a wide temperature control range within a limited response time, a response rate is decreased, and control may be unstable in a region close to a target temperature.
FIG. 2 illustrates an example of a heating method using a thermoelectric element block. A thermoelectric element block 100 is configured in such a way that a thermoelectric element 105 surrounds a flow passage 101 of a refrigerant so as to improve the efficiency of the thermoelectric element 105, and cold air in a heat absorption surface that is generated when a heating operation of the thermoelectric element 105 is performed is discharged via PCW flow passages 102 and 103.
As a result, the thermoelectric element 105 must be controlled at a higher temperature than the refrigerant so as to heat the refrigerant. For example, the thermoelectric element 105 must be controlled to a temperature of 110° C. or more so as to heat the refrigerant to 90° C. However, due to characteristics of the thermoelectric element 105, when the thermoelectric element 105 is at 60° C. or more, the thermoelectric element 105 is rapidly deteriorated. Thus, it is difficult to use the thermoelectric element 105 to control a temperature range of 60° C. or more.
Furthermore, since an electronic chiller having the above configuration maintains the temperature of a working load using a refrigerant, a control manipulation amount for varying the temperature of a large amount of refrigerant is actually larger than a temperature control amount to be controlled. That is, a control manipulation amount for controlling a narrow temperature control range increases considerably. Thus, even though a response property is improved by reducing the size of hysteresis through linear control by PID control and polarity control, control must first be performed with a large value for a narrow temperature control range. Thus, when cooling and heating are performed using a single thermoelectric element, a PID output amount and polarity for maintaining a desired temperature vary frequently. For example, even when a value that is 1° C. different from the desired temperature is detected, temperature control of the thermoelectric element can be performed within a desired control time at which the thermoelectric element must be changed to a temperature that is several times the desired temperature so as to adjust the different value to the desired temperature. In order to adjust the desired temperature, temperature control must be performed by varying cooling and heating. A voltage having a large value crosses different polarities and is applied to the thermoelectric element. This causes the life span of the thermoelectric element to be reduced, and the desired temperature not to converge on the target temperature but to continuously vary due to polarity crossing of a large control amount. A control unstable region in which a control output and an actual temperature vary for a relatively long time in the vicinity of the desired temperature is referred to as a dead zone.
As a temperature range to be controlled increases, the range of a setting temperature increases and a control manipulation amount increases, and thus control instability in the dead zone becomes severe.
As a result, a chiller using a new method whereby an effective response to a wide temperature control range including a high temperature region can be performed while using a thermoelectric element that is capable of performing precise temperature control, unstable control caused by the dead zone can be prevented and a power-saving operation can be performed in consideration of energy efficiency is required.